Zipvit sport l arginine is a high strength formulation in recent studies by researchers at the university of exeter it was discovered that supplementing with l arginine improved levels of nitric oxide in endurance athletes which may increase stamina levels reference bailey sj winyard pg vanhatalo a blackwell jr dimenna fj wilkerson dp jones amacute l arginine supplementation reduces the o2 cost of moderate intensity exercise and enhances high intensity exercise tolerancej appl physiol